In recent years, solid-state light sources such as LEDs or semiconductor lasers have been widely commercially available or suggested as light sources for large high-brightness projectors intended for large halls or digital cinemas, for small to medium sized projectors intended mainly for a small number conference or presentation, and for projection monitors including, in its casing, a projection optical system and a large screen. In these devices, the conventional lamps used as the light sources for many projectors and projection monitors are replaced by the solid-state light sources. Accordingly, these devices have advantages of, for example, wider color gamut, instant light capability, low power consumption, and long life.
Particularly, the semiconductor lasers have additional advantages of higher brightness and higher output through superposition of light. Thus, high-output semiconductor laser light source devices using a larger number of semiconductor lasers are being developed for use in large high-brightness projectors that project large screens.
However, the semiconductor lasers are more heat-sensitive than the other solid-state light sources such as LEDs, and the electrical-to-optical efficiency thereof is prone to extremely decrease according to increase in temperature of the elements. Furthermore, the continued emission of high-output light at high temperatures expedites degradation of the elements and tends to shorten the life thereof. Thus, the semiconductor lasers require a heat dissipation structure with cooling capability higher than those of the other solid-state light sources to obtain a desired amount of light even when the ambient temperature is high.
For example, Patent Document 1 discloses a structure including rectangular tine shaped radiating fins placed on a base equipped with a semiconductor laser, and a cooling fan fixed to the radiating fins with a driving substrate having holes interposed therebetween.
Furthermore, Patent Document 2 discloses a structure in which a flexible substrate for electrically connecting semiconductor lasers is embedded in a heat transfer component or in a base of a heat sink to dissipate heat from the semiconductor lasers.